While endothelial dysfunction is known to be a part of preeclampsia (PE), the molecular basis for endothelial dysfunction remains unclear. Current therapies for the associated hypertension are still largely targeted to relaxation of vascular smooth muscle and yet this is not sufficient to fully control the disorder. New strategies are needed based on novel approaches to therapeutic intervention. This will only be possible given a clearly identified new therapeutic target and a means to screen it at the level of endothelial function. Such large scale screening approaches require large numbers of high purity, well characterized cells from PE subjects. Second round testing in resistance level vessels can then be undertaken on a realistic scale before moving towards drug refinement and trials in human subjects. The problem remains that human uterine artery tissue from normal and PE pregnancy are not sufficiently available to undertake the initial screen, and smaller vessel biopsy samples are insufficient to yield cells of high enough purity or quantity for drug panel screening. Our preliminary data suggests that while vascular endothelial function is indeed maximized in the uterine artery in normal pregnancy, these same mechanisms are also observed and maximized in other vascular beds including fetoplacental vessels such as the umbilical vein. Further, these signaling events and associated NO production in the endothelium of normal cords also appear to have failed in PE subjects. Thus, in order to establish if it is possible to use HUVEC from PE subjects as suitable cells in such a drug screen we propose: SpAim 1: Hypothesis: The observed sustained [Ca2+]i bursts in responses to ATP in intact UV Endo from normal pregnancy are due to TRPC3 and CX43 activation, and losses of Ca2+ burst associated with strategies aimed at TRPC3 or CX43 inhibition replicate the lower/blunted Ca2+ and NO responses seen in PE subjects. SpAim 2 (Transitional to Aim 3): Hypothesis: PE associated dysfunction in PE derived UV Endo or PE derived HUVEC (passage 3) compared to that from normal subjects is not due to simple changes in the relative levels of expression of P2Y2 receptors, G proteins, PLC, IP3 receptors, TRPC channels, or connexins. SpAim 3: Hypothesis: In short term culture, the sustained [Ca2+]i burst responses to ATP in HUVEC from normal pregnancy due to CX43 potentiation of IP3 sensitive TRPC3 activation are retained, and are lacking in cells derived from PE subjects. Further, inhibition of either IP3 mediated TRPC3 activation or CX43 mediated cell-cell communication in HUVEC from normal subjects replicates the loss of function seen in HUVEC from PE subjects, but does not further inhibit the function of HUVEC from PE subjects. Given success, the ready availability of cords and large yields of UV Endo cells from PE subjects means that future large scale drug testing could be performed, even with additional focus on targeted/disadvantaged subpopulations of the public. This could allow more selective intervention with new drugs or new applications of existing drugs that impact on this signaling pathway, and so relieve the devastating effects of preeclampsia.